Moisture- and high-temperature treatment of fabrics before finishing operations

ABSTRACT

IN A PROCESS FOR THE FINISHING OR CONDITIONING OF TEXTILES IN FARIC FORM, INCLUDING BLEACHING, DYEING, TREATMENT AFTER PRINTING OR FINAL OR ADVANCED FINISHING IN WHICH THE TREATED FABRIC IS, AFTER IMPREGNATION WITH THE TREATMENT MEDIUM, EXPOSED TO A HEAT TREATMENT, THE IMPROVEMENT WHICH COMPRISES THE FABRIC TO BE TREATED AFTER IMPREGNATION AND BEFORE UNDERGOING A HEAT TREATMENT TO A MOISTURE CONTENT, RANGING FROM 10 PERCENT ABOVE TO 15 PERCENT BELWO SATURATION CONTENT IN THE CASE OF FABRICS CONSISTING PREDOMINANTLY OF NATURAL OR ABSORBENT FIBERS AND WHICH RANGES FROM 10 PERCENT BELOW TO 10 PERCENT ABOVE SATURATION IN THE CASE OF FABRIC CONSISTING OF PREDOMINANTLY LESS ABSORBENT CHEMICAL OR MAN-MADE FIBERS AND THEREUPON SUBJECTING THE FABRIC TO A TREATMENT BY HEAT IN A MEDIUM CONSISTING OF STEAM OR A A STAM/AIR MIXTURE UNDER SUPER PRESSURE, THE VAPOR PRESSURE OR PARTIAL PRESSURE WHEREOF DOES NOT EXCEED 25 ATMOSPHERES ABSOLUTE.

United States fiatent 6 MOISTURE- AND HIGH-TEMPERATURE TREAT- MENT OF FABRICS BEFORE FINISHING OPERATIONS Christian August Meier-Windhorst, Hamburg, Germany,

assignor to Artos Dr. Ing. Meier-Wiudhorst Kommanditgesellschaft, Heidenkampsweg, Germany N Drawing. Filed June 9, 1971, Ser. No. 151,533

Int. Cl. D06c 1/06 US. Cl. 8-1493 6 Claims ABSTRACT OF THE DISCLOSURE In a process for the finishing or conditioning of tex tiles in fabric form, including bleaching, dyeing, treatment after printing or final or advanced finishing in which the treated fabric is, after impregnation with the treatment medium, exposed to a heat treatment, the improvement which comprises the fabric to be treated after impregnation and before undergoing a heat treatment to a moisture content, ranging from 10 percent above to percent below saturation content in the case of fabrics consisting predominantly of natural or absorbent fibers and which ranges from 10 percent below to 10' percent above saturation in the case of fabric consisting of predominantly less absorbent chemical or man-made fibers and thereupon subjecting the fabric to a treatment by heat in a medium consisting of steam or a steam/ air mixture under super pressure, the Vapor pressure or partial pressure whereof does not exceed atmospheres absolute.

This invention relates to a process in which hitherto unattainable optimum conditions are made available for the action of chemicals on the surface of fibers and for the fixing of dyes and other finishing substances on the surface and in the interior of fibrous material, preferably in the form of continuous textile cloths or webs.

The process finds the application principally in bleaching, dyeing, after-treatments following printing, and treatment with special finishes, such as non-creasing finishes, waterproofing and similar methods of final and high-grade finishing, as Well as in the treatment by heat of man-made woven and knitted fabrics.

In the first of the aforementioned treatments, the material to be treated is first wetted, impregnated or printed with a bleaching agent, a dye, or the finishing agent.

In bleaching, in most dyeing processes and in the socalled two-stage process of cloth printing, the textile cloths are passed to the usual after-treatment at elevated temperatures in a moist or normally squeezed or wrung condition, i.e., with a moisture content of between 70 to 150 percent compared to the dry condition. These aftertreatments, whether in the moist or dry state, are conducted according to the nature of the treatment at normal atmospheric pressure in steam, in steam/air mixture, or in air. In such a case, the textile cloths are passed through a number of different paths, either in a continuous open band or over continuously rotating stock rolls.

The basic principle of conducting the above treatments includes maintaining treatment stages at elevated temperatures under normal pressure in two very different ranges of humidity, namely, 3 to 12 percent, and 70 to 150 percent, which may in particular cases, to some extent, be combined into a single range of 12 to 70 percent.

An upper limit to the treatment temperature of 100 C. is disadvantageous for treatment in a higher range of humidity. It is preferred to attain shorter treatment times, or to transfer one or the other treatment from the dry to the Wet phase (e.g., the transition from a single stage to a two-stage printing process), and this prefer- 3,695,826 Patented Oct. 3, 1972 ence has recently called for investigations into the possibility of a continuous or semi-continuous heat treatment at above atmospheric pressure, thus enabling temperatures above 100 C. to be used.

In the substantial development of the above-mentioned investigations, a novel process is now proposed for the continuous or semi-continuous heat treatment at elevated pressure and advanced working conditions, affording surprisingly good processing results, in particular, in regions in which the normal pressure methods hitherto known have hardly, if ever, been used.

Such a novel process is the object of the present invention. Certain fundamental considerations have shown that if particular pressure values are exceeded-specifically certain steam pressures or partial vapor pressures of the processing medium, the most favorable conditions are obtained for particular finishing processes when the textile cloths to be treated are .handled, neither in the wet condition, nor in the dry condition, but with certain mean humidity percentages.

The above-mentioned investigations have further shown that in the case of heat treatment at elevated pressure in pure steam or in a steam/ air mixture, in application to bleaching treatment, dyeing processes, after treatment by pressure and final and advanced finishing processes, as well as for stabilizing or fixing man-made fiber textiles or knitted goods, optimum processing results can be ob tained of the degree of humidity at the entry relative to the dry condition of the material is maintained in cloths consisting of natural fibers at not more than 10 percent above and 15 percent below the saturation humidity content of the fiber; and in cloths consisting predominantly of man-made fibers, not more than 10 percent above or below the same humidity content, While the steam pressure or partial vapor pressure of the steam in the heat treatment medium is maintained above a pressure of 2.5 atmospheres absolute.

In order to fulfill these conditions, a carefully controlled water removal process following saturation with the treatment medium is required in all bleaching, dyeing and final or advanced finishing processes.

This may consist in high pressure squeezing or wringing of the cloth treated, in the case of fibers with low water absorption following or associated with previous saturation, to reduce it to the required moisture contents. The requisite accurate adjustment of this intermediate moisture content is obtained by continuous measurement of the humidity content with the use of available instruments and a suitably automatic regulation of the squeezing or wringing effect.

In the majority of cases, water removal after saturation with the treatment medium, particularly in the case of fibers with low Water absorption, can be conducted by ordinary drying. The required intermediate humidity con- EXAMPLE 1 Moisture adjustment by squeezing A length of web is continuously passed through one of the conventional elongated troughs used in textile treatments. When entering the trough, the fiber has a Water content of 8%. While passing through the trough, at the rate of 1 yard per second, the fiber is squeezed between rollers, arranged above and below the path of the web, and adjusted to exert a pressure on the fiber of 34 kg./ cm. thereby steadily reducing the Water content of the web during the passage. The water removed from the fabric is drained by appropriate pipes, Equipment is further provided on the trough for measuring the moisture content and for re-adjusting the pressure of the squeezing rolls when it is found unsatisfactory. When the web leaves the trough, the moisture content is found to be 20% below saturation.

The following heat treatment of the web, if desired combined with another textile finishing treatment, is carried out in pressure apparatus at 2.5 atm. absolute.

EXAMPLE 2 Moisture adjustment by drying A length of web is passed over an endless belt in a drying apparatus known in textile processing. In this case, it is intended to reach the desired moisture content by partial drying, which, with a given temperature of the heating gas, can be obtained by controlling the rate of travel. The water content of the fabric is 40% above saturation at the entry of the fabric into the drier and it is intended to reach a moisture content of 5% above saturation. With a temperature of 150 C. obtaining in the drier, the rate of travel should be 1.2 yards/ second. The apparatus is equipped with measuring instruments for the intermediat and the final humidity and for adjusting the rate of travel in accordance with the loss of moisture, which escapes as steam through pipes provided therefor. In cases in which discontinuous operation of the saturating (steeping) and drying stages is required, in particular when wide-stretching or tentering is interposed, the cloth under treatment is in the first instance fully dried, and is then brought to the required, intermediate humidity content by carefully-controlled damping or spraying.

When intermediate drying, either partial or complete, is used, it will be found particularly advantageous, following on a dyeing or final or advanced conditioning stage, to conduct the drying in a first stage to 45 to 55% humidity (the so-called pre-drying) as a slow-drying stage, with low, specific drying performance, and in addition, to precede this with a diifusion or conditioning stage directly following the saturation or impregnation stage, without the use of drying means or with only a very low degree of drying. It has been found that this diffusion stage ensures optimum distribution of the impregnating liquid, which optimum distribution is not disturbed by the following diffusion conditioning stage. The positive benefits of the process according to the present invention, are thus given full play.

In finishing processes in which the treatment effects are particularly obtained is the surface layer of the fibers, the process according to the present invention is advantageously conducted, particularly in the case of natural fibers and mixtures therewith, in combination with a so-called addition-impregnation. This consists in first charging the interior of the fiber in a first impregnation stage with a neutral treatment solution, followed after high-effect squeezing or a first intermediate drying, by applying a highlyconcentrated liquor so to speak additively, to the material under treatment. When using the method according to the present invention, such an impregnating treatment is in every case applied before the high-pressure treatment, suitably with further, intermediate drying. This, on

the one hand, ensures a suitable degree of humidity inside the fibres, for the optimum development of the following reactions, and, on the other hand, a considerably reduced consumption of treatment media while maintaining an optimum concentration of the treatment liquors within the fibers to be treated.

The present invention is also a device or installation for carrying out the process according to the present invention.

What is claimed is:

1. In a process for the finishing or conditioning of textiles in fabric form, including bleaching, dyeing, treatment after printing or final or advanced finishing in which the treated fabric is, after impregnation with the treatment medium, exposed to a heat treatment, the improvement which comprises bringing the fabric to be treated, after impregnation and before undergoing a heat treatment, to a moisture content ranging from 10% above to 15% below saturation content in the case of fabrics consisting predominantly of natural or absorbent chemical or man-made fibers and thereupon subjecting the fabric to a treatment by heat in a medium consisting of steam or a steam/air mixture under super pressure, the vapor pressure or partial pressure whereof does not exceed 2.5 atmospheres absolute.

2. The process in accordance with claim 1, in which the fabric to be treated is immediately after or during saturation with the processing medium subjected to a separate, powerful squeezing action, with automatic regulation by concurrent intermediate measurement of the moisture content, until the required intermediate value of the said moisture content is attained.

3. The process in accordance with claim 1, in which the fabric to be treated is immediately after a wet-treatment subjected to a drying treatment automatically controlled by concurrent, intermediate measurement of the moisture content until the required value of such intermediate moisture content is attained.

4. The process in accordance with claim 1, in which the fabric after being fully dried is brought by a conditioning treatment for moisturizing or by a mechanical contact or spray moisturizing operation controlled by continuous, intermediate measurement of the moisture content to the required degree of intermediate humidity.

5. The process in accordance with claim 3, in which at least the first stage of the drying treatment after the wet treatment or impregnation is conducted as a slow drying and is suitably linked with a diffusion period for a minimum drying effect.

6. The process in accordance with claim 1, in which the fabric to be treated is in a final or advanced finishing treatment following one of the treatments preceding the heat treatment under pressure, subjected to a Wide-stretching or tentering treatment.

References Cited UNITED STATES PATENTS 1,907,429 5/1933 Masland 8-1493 3,088,224 5/1963 Cohn et al. 3437 X 3,264,748 8/ 1966 Meier-Windhorst 34l2 3,553,845 1/1971 Lee et a1 34-9 WllLIAM I. PRICE, Primary Examiner U.S. Cl. X.R. 

